UC Berkeley Looks for Galaxy X

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The distribution of Hl hydrogen in the Whirlpool Galaxy (M51) as determined by the THINGS VLA survey extends far beyond the visible stars in the galaxy and its satellite, NGC5195 (marked by cross), which is situated in the short arm of the spiral. Analysis of perturbations in the hydrogen distribution can be used to predict the location of such satellites, in particular, those satellites that are composed primarily of dark matter and are thus too faint to be detected easily. Credit: Sukanya Chakrabarti/UC Berkeley

Updated at 3:17 PM PST on Thursday, Jan 13, 2011

Scientists at University of California, Berkeley have developed a method that may help find Galaxy X, a dwarf galaxy orbiting ours.

In a press release, theoretical astronomer Sukanya Chakrabarti explains how she has found a way to locate "dark" satellite galaxies by analyzing the ripples in the hydrogen gas distributed in spiral galaxies, such as our Milky Way.

"The method is like inferring the size and speed of a ship by looking at its wake," said Blitz. "You see the waves from a lot of boats, but you have to be able to separate out the wake of a medium or small ship from that of an ocean liner."

Earlier this year, Chakrabarti used her mathematical method to predict that a dwarf galaxy sits on the opposite side of the Milky Way, but is not able to be seen due to gas and dust in the galaxy's disk.

Chakrabarti and Blitz also calculated that the predicted galaxy is in a parabolic orbit around the Milky Way, now at a distance of about 300,000 light years from the galactic center. The galactic radius is about 50,000 light years.

"Our paper is a proof of principle, but we need to look at a much larger sample of spiral galaxies with optically visible galactic companions to determine the incidence of false positives," and thus the method's reliability, Chakrabarti said.